Reinforced structure, fiber sheet and crack detection method

Abstract

To suppress a detection failure of cracks in a structure in a configuration of detecting cracks in a structure by breaking an insulation layer and light emission by illumination.SOLUTION: A reinforcement structure includes a fiber sheet 40 disposed on a surface of a structure 90 and including fibers which emits light when illuminated, and an insulation layer 50 which adheres to a surface of the fiber sheet 40 and insulates light illuminated on the fiber sheet 40. When a push-out load test is carried out for the fiber sheet 40 and insulation layer 50, the insulation layer 50 breaks before the fiber sheet 40 breaks.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a reinforcement structure, a fiber sheet, and a crack detection method. [Background technology]

[0002] Patent Document 1 discloses a method for inspecting deterioration of a structure, which comprises forming a highly elastic first coating layer on a base constituting the structure, which contains a fluorescent dye that emits light when exposed to excitation light and which stretches without breaking even when a crack occurs in the base, and forming a low-elastic second coating layer on this first coating layer, which contains a shielding material that blocks the transmission of excitation light and which generates cracks in response to cracks that occur in the base when they occur, and then irradiating the structure with excitation light to detect cracks that occur in the base after the coating layer formation by passing the excitation light through the cracks that occur in the second coating layer and causing the first coating layer to emit light.

[0003] Patent Document 2 discloses a concrete structure comprising a base made of concrete, a first layer formed on the surface side of the base, and a second layer formed on the surface side of the first layer, wherein the first layer contains a polymer including polyacrylate or a crosslinked product thereof and a fluorescent whitening agent, and the second layer contains a polymer including an acrylic silicone resin or a crosslinked product thereof or a fluorine-containing resin and an ultraviolet absorber, and wherein the tensile breaking elongation of the membrane constituting the first layer, measured in accordance with JIS A 6021, is at least 50% higher than the tensile breaking elongation of the membrane constituting the second layer, the tensile breaking elongation of the membrane constituting the first layer being 100% to 2,000%, and the tensile breaking elongation of the membrane constituting the second layer being 10% to 200%.

[0004] Patent Document 3 discloses a method for warning of damaged areas, characterized in that a light-emitting layer is formed on the lower side of a substrate surface layer, such as a topcoat layer applied to the substrate, when irradiated with light; when damage such as a crack occurs in the substrate surface layer, the light-emitting layer at that location is irradiated with incident light from the damaged area, causing it to emit light, and this light emission issues a self-alarm to the outside. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5562310 [Patent Document 2] Patent No. 5664520 [Patent Document 3] Japanese Patent Application Publication No. 8-159976 Summary of the Invention [Problem to be solved by the invention]

[0006] A structure comprising a light-emitting layer coated on the surface of a structure and having a light-emitting material dispersed therein, and a shielding layer coated on the surface of the light-emitting layer and having a shielding material dispersed therein, in which the elongation of the shielding layer is smaller than that of the light-emitting layer so that only the shielding layer breaks when a crack occurs in the structure, has the following effect: That is, in the above structure, when a crack occurs in the structure, if the light-emitting layer stretches and only the shielding layer breaks, when light is irradiated toward the shielding layer, the light passes through the broken part of the shielding layer, causing the light-emitting layer to emit light, and the crack that has occurred in the structure can be detected.

[0007] However, with the above structure, it is difficult to adjust the elongation of the shielding layer and the light-emitting layer so that only the shielding layer breaks when a crack occurs in the structure, and if a crack occurs in the structure and both the shielding layer and the light-emitting layer break, it becomes impossible to detect the crack in the structure.

[0008] The present invention aims to suppress failure to detect cracks in a structure when detecting cracks in the structure by light emission caused by irradiation with light. [Means for solving the problem]

[0009] The reinforcing structure of the first embodiment comprises a fiber sheet placed on the surface of a structure and containing fibers that emit light when irradiated with light, an adhesive layer that adheres the fiber sheet to the surface, and a shielding layer that blocks light irradiated onto the fiber sheet, and when a punching load test is performed on the fiber sheet, the adhesive layer, and the shielding layer, the adhesive layer and the shielding layer break before the fiber sheet.

[0010] According to the reinforced structure of the first aspect, the fiber sheet is disposed on the surface of the structure, thereby reinforcing the structure.

[0011] Here, in the reinforced structure of the first embodiment, when a punching load test is performed on the fiber sheet, adhesive layer, and shielding layer, the adhesive layer and shielding layer break before the fiber sheet. In the punching load test, a tensile force in a direction along the surface of the structure and a shear force in a direction normal to the surface act on the fiber sheet, adhesive layer, and shielding layer. Therefore, in the reinforced structure of the first embodiment, when a tensile force in a direction along the surface of the structure or a shear force in a direction normal to the surface act on the fiber sheet, adhesive layer, and shielding layer, the adhesive layer and shielding layer break before the fiber sheet. Therefore, when a crack occurs in the structure and the surface of the structure expands in a direction along the surface, or when a crack occurs in the structure and the surface of the structure shifts in the shear direction, the adhesive layer and shielding layer can break, exposing the fiber sheet.

[0012] As a result, when light is irradiated toward the shielding layer, the exposed fiber sheet emits light, making it possible to detect cracks that have occurred in the structure. In this structure, the light-emitting body that emits light when irradiated with light is the fiber sheet, so even if the surface of the structure spreads in a direction along the surface or if a shear displacement occurs in the surface of the structure, it is possible to create a structure in which the light-emitting body is less likely to break, thereby reducing the possibility of failure to detect cracks in the structure.

[0013] The second embodiment of the reinforcing structure comprises a fiber sheet placed on the surface of a structure and containing fibers that emit light when irradiated with light, an adhesive layer that adheres the fiber sheet to the surface, and a shielding layer that blocks light irradiated onto the fiber sheet; when a crack occurs in the structure, the adhesive layer and the shielding layer break, exposing the fiber sheet from the broken portion.

[0014] According to the reinforced structure of the second aspect, the fiber sheet is placed on the surface of the structure, so that the structure is reinforced.

[0015] In the reinforced structure of the second embodiment, when a crack occurs in the structure, the adhesive layer and the shielding layer break, exposing the fiber sheet from the broken portion. Therefore, when light is irradiated toward the shielding layer, the exposed fiber sheet emits light, allowing the crack to be detected.

[0016] Furthermore, in this structure, the light-emitting element that emits light when exposed to light is a fiber sheet, so even if a crack occurs in the structure, the light-emitting element is less likely to break, thereby reducing the risk of failure to detect cracks in the structure.

[0017] In the reinforcement structure of the third aspect, the shielding layer also serves as the adhesive layer.

[0018] According to the reinforcement structure of the third aspect, the shielding layer also serves as an adhesive layer, so that a material for adhering the fiber sheet is not required in addition to a material for forming the shielding layer.

[0019] The fiber sheet of the fourth embodiment is a fiber sheet that is placed on the surface of a structure to reinforce the structure, and contains fibers that emit light when irradiated with light.

[0020] The fiber sheet of the fourth aspect can be placed on the surface of a structure to reinforce the structure. Furthermore, by using the fiber sheet of the fourth aspect in the reinforcing structures of the first and second aspects, the fiber sheet emits light, making it possible to detect cracks that occur in the structure.

[0021] Furthermore, in this structure, the light-emitting element that emits light when exposed to light is a fiber sheet, so even if a crack occurs in the structure, the light-emitting element is less likely to break, thereby reducing the risk of failure to detect cracks in the structure.

[0022] The crack detection method of the fifth aspect detects cracks that have occurred in a structure by irradiating light onto the reinforcement structure of any one of the first to third aspects and detecting the luminescence of the fiber sheet.

[0023] In the reinforcement structures of the first to third aspects used in the crack detection method of the fifth aspect, the light-emitting body that emits light when irradiated with light is a fiber sheet, so even if a crack occurs in the structure, the light-emitting body is less likely to break. Therefore, the crack detection method of the fifth aspect can reduce failures in detecting cracks in the structure. [Effects of the Invention]

[0024] The present invention has the above-described configuration, and therefore has the excellent effect of being able to suppress failure to detect cracks in a structure when detecting cracks in the structure by light emission caused by irradiation with light. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view showing a reinforcement structure according to a first embodiment. [Figure 2] 3 is a cross-sectional view showing a state in which the shielding layer is broken in the reinforcement structure according to the first embodiment. FIG. [Figure 3] FIG. 10 is a cross-sectional view showing a comparative structure. [Figure 4] FIG. 10 is a cross-sectional view showing a comparative structure in which the shielding layer and the light-emitting layer are broken. [Figure 5] FIG. 6 is a cross-sectional view showing a reinforcement structure according to a second embodiment. [Figure 6] 10 is a cross-sectional view showing a state in which the shielding layer and the adhesive layer are broken in the reinforcement structure according to the second embodiment. FIG. [Figure 7] FIG. 1 is a diagram showing an outline of a push-out load test. [Figure 8]1 is a graph showing the relationship between load and displacement in a push-out load test. [Figure 9] 1 is a photograph showing luminescence from a fiber sheet in an evaluation test. [Figure 10] 1 is a graph showing the measurement results of elongation at break in Examples. [Figure 11] 10 is a graph showing the measurement results of breaking elongation in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0026] An example of an embodiment of the present invention will be described below with reference to the drawings. First Embodiment (Reinforcement structure 10) First, a reinforcement structure 10 according to this embodiment will be described. Fig. 1 is a cross-sectional view showing the reinforcement structure 10 according to this embodiment. Fig. 2 is a cross-sectional view showing the reinforcement structure 10 according to this embodiment in a state where a shielding layer 50, which will be described later, is broken.

[0027] The reinforcement structure 10 shown in Fig. 1 is a structure that reinforces a structure 90 and prevents the structure 90 from spalling or falling off. An example of the structure 90 is a concrete structure. An example of the concrete structure is a lining wall of a railway or road tunnel.

[0028] The concrete structure is not limited to the lining walls of railway or road tunnels, but may be, for example, a building, a bridge, a bridge pier, etc., as long as it is a structure to be reinforced. Furthermore, the structure is not limited to concrete, but may be, for example, a structure made of mortar, ceramics, metal, glass, etc., as long as it is a structure to be reinforced.

[0029] 1, the reinforcement structure 10 specifically includes a primer 20, an unevenness correction material 30, a fiber sheet 40, and a shielding layer 50. In the reinforcement structure 10, the primer 20, the unevenness correction material 30, and the shielding layer 50 are laminated in this order, and the fiber sheet 40 is disposed inside the shielding layer 50.

[0030] The primer 20 is applied to the surface of the structure 90. The primer 20 has the function of improving the bonding (adhesion) between the structure 90 and a layer formed on the structure 90. As an example, a resin such as an epoxy resin is used for the primer 20. Note that the primer 20 is not limited to an epoxy resin, and may be, for example, a resin other than an epoxy resin, such as a thermosetting resin, and various other materials can be used.

[0031] The unevenness correction material 30 is applied to the surface of the primer 20. The unevenness correction material 30 has the function of smoothing out the irregularities on the surface of the structure 90. As an example, a resin such as an epoxy resin is used for the unevenness correction material 30. Note that the unevenness correction material 30 may be a resin other than epoxy resin, such as a thermosetting resin, and various other materials may be used.

[0032] The fiber sheet 40 is placed on the surface of the unevenness correction material 30. That is, the fiber sheet 40 is placed on the surface of the structure 90 to which the primer 20 and the unevenness correction material 30 have been applied. Note that the entire structure 90 to which the primer 20 and the unevenness correction material 30 have been applied may be considered as the "structure" in the claims.

[0033] The fiber sheet 40 has the function of reinforcing the surface of the structure 90. The fiber sheet 40 contains fibers (hereinafter referred to as luminous fibers) that emit light when irradiated with light (specifically, ultraviolet light).

[0034] The luminescent fiber is made of a thermoplastic resin containing a luminescent material that emits light when irradiated with light. Examples of the thermoplastic resin used for the luminescent fiber include polyester, nylon, polyolefins such as polypropylene, vinylon, and the like. The resin used for the luminescent fiber is not limited to the above, and other resins may also be used. Furthermore, the luminescent fiber may be a composite fiber with carbon fiber or glass fiber.

[0035] As an example of the luminous material used in the luminous fiber, a phosphorescent material is used that stores irradiated light and continues to emit light even after the light irradiation stops. Examples of phosphorescent materials include phosphorescent pigments using strontium aluminate. The luminescent material may also be a fluorescent material that emits light when irradiated with light and stops emitting light when the light irradiation stops, or may be an inorganic fluorescent material such as a rare earth activated metal oxide, or an organic fluorescent material such as a fluorescent dye or a fluorescent brightener, as long as it emits light when irradiated with light.

[0036] The luminescent fiber is formed into a thread-like luminescent fiber by spinning a thermoplastic resin containing a luminescent material. Examples of the spinning method include melt spinning, dry spinning, and wet spinning.

[0037] In melt spinning, the raw material is melted by heat, extruded through a spinneret to form fibers, and then cooled and solidified. In dry spinning, the raw material is dissolved in a solvent that vaporizes by heat, and extruded through a spinneret in a hot atmosphere to evaporate the solvent and form fibers. In wet spinning, the raw material is dissolved in a solvent, and extruded through a spinneret in a solution called a coagulation bath to cause a chemical reaction, and then the solvent is removed to form fibers.

[0038] The luminescent fiber may be a bundle or twist of spun luminescent fibers. Furthermore, the luminescent fiber may be a luminescent fiber obtained by subjecting a spun fiber (fiber not containing a luminescent material) to a surface treatment with a chemical containing a luminescent material.

[0039] Although a nonwoven fabric using short fibers can be used for the fiber sheet 40, a continuous fiber sheet using continuous fibers is preferable from the viewpoint of strength, detection performance, etc. Specifically, the fiber sheet 40 may be a UD (Unidirectional) material (i.e., a unidirectional material in which fibers are aligned in one direction) made of luminescent fiber, a woven fabric, a knitted fabric, or the like. Examples of woven fabrics include those woven by plain weave, twill weave, satin weave, etc. Examples of knitted fabrics include weft knitted fabrics such as plain knit, rib knit, and purl knit, and warp knitted fabrics (tricot, etc.) such as denbi knit, cord knit, and atlas knit.

[0040] The fiber sheet 40 need not be entirely made of luminescent fibers, as long as it contains luminescent fibers. In other words, the fiber sheet 40 may contain non-luminescent fibers that do not emit light. For example, a woven fabric can be used in which one of the warp and weft threads is luminescent fiber and the other is non-luminescent fiber. The fiber sheet 40 may contain, for example, 5% [vol%] or more of luminescent fibers.

[0041] Furthermore, multiple fiber sheets 40 may be stacked as the fiber sheet 40. When multiple UD materials are stacked, they are used, for example, stacked so that the fiber directions of the sheets are perpendicular to each other. This allows the fibers to be aligned in the perpendicular direction, increasing the tensile strength in the perpendicular direction and improving the reinforcing effect of the fiber sheet 40. Also, a UD material made of non-luminescent fibers and a UD material containing luminescent fibers can be stacked. Note that even when woven fabrics, knitted fabrics, etc. are used as the fiber sheet 40, multiple fiber sheets 40 may be stacked.

[0042] The light that causes the fiber sheet 40 to emit light is not limited to ultraviolet light, but may be blue light (blue visible light), for example, and various other types of light can be used.

[0043] The shielding layer 50 has the function of blocking light irradiated onto the fiber sheet 40. The shielding layer 50 contains a shielding material that blocks light.

[0044] Specifically, the shielding layer 50 is formed by applying a resin containing a shielding material (hereinafter referred to as a shielding resin) to the surface of the unevenness correcting material 30 and then curing the resin. The shielding layer 50 also has the function of adhering the fiber sheet 40 to the surface of the unevenness correcting material 30.

[0045] As an example, a resin such as an epoxy resin is used for the shielding layer 50. Note that the material for the shielding layer 50 is not limited to epoxy resin, and may be a thermosetting resin other than epoxy resin, such as an acrylic resin, and various materials may be used, but a solvent-free room-temperature curing epoxy resin is preferably used.

[0046] The shielding material may be any material that can physically or chemically shield the light (specifically, ultraviolet light) that causes the fiber sheet 40 to emit light, and inorganic fillers or absorbents are used.

[0047] The inorganic filler as a shielding material is not particularly limited in material or shape as long as it can physically block the light that causes the fiber sheet 40 to emit light, but carbon black or titanium oxide is preferably used.

[0048] The absorbent used as the shielding material is capable of chemically absorbing the light that causes the fiber sheet 40 to emit light. When the light that causes the fiber sheet 40 to emit light is ultraviolet light, an ultraviolet absorbing material that absorbs ultraviolet light is used as the shielding material. Note that the ultraviolet absorbing material may also absorb light of wavelengths other than ultraviolet light. Furthermore, the shielding material may be a combination of the inorganic filler and the absorbent.

[0049] The shielding layer 50 is an example of a shielding layer in the claims, and is also an example of an adhesive layer in the claims. That is, the shielding layer 50 also serves as an adhesive layer.

[0050] Here, in the reinforcement structure 10, when a punching load test is performed on the fiber sheet 40 and the shielding layer 50, the shielding layer 50 breaks before the fiber sheet 40. In the punching load test, a tensile force in a direction along the surface of the structure 90 (hereinafter referred to as the planar direction) and a shear force in a direction normal to the surface act on the fiber sheet 40 and the shielding layer 50. Therefore, in the reinforcement structure 10, when a tensile force in the planar direction or a shear force in the direction normal to the surface of the structure 90 acts on the fiber sheet 40 and the shielding layer 50, the shielding layer 50 breaks before the fiber sheet 40.

[0051] Therefore, when a crack occurs in the structure 90 and the surface of the structure 90 expands in the planar direction, or when a crack occurs in the structure 90 and a displacement in the shear direction occurs on the surface of the structure 90, the shielding layer 50 breaks while the fiber sheet 40 remains intact, as shown in Fig. 2. Therefore, the reinforcement structure 10 is configured such that when a crack occurs in the structure 90, the shielding layer 50 breaks and the fiber sheet 40 is exposed from the broken portion.

[0052] For example, the "Punching Load Test" described in Appendix 17-2, Test Methods for Concrete Surface Coating Methods, of the Standard Specifications for Civil Engineering Works (edited by East Japan Railway Company) and the Japan Railway Facilities Association (September 2016) is used as the punching load test.

[0053] Furthermore, in the reinforcement structure 10, when the fiber sheet 40 and the shielding layer 50 are compared in terms of tensile elongation (elongation) in the plane direction, the fiber sheet 40 has a greater tensile elongation (elongation) than the shielding layer 50. Specifically, the elongation of the fiber sheet 40 is, for example, 20-odd%, and the elongation of the shielding layer 50 is, for example, 3% or less, preferably 0.5% to 3%, and more preferably 0.5% to 2.5% (all elongations at 23°C). Note that this elongation is the breaking elongation (i.e., the value obtained by dividing the elongation between the gauge points of the tensile test piece after breaking by the gauge length and expressing it as a percentage).

[0054] In addition, the reinforcing structure 10 may have a protective layer formed on the surface of the shielding layer 50 to protect the shielding layer 50. The protective layer is formed to protect the shielding layer 50 from deterioration due to ultraviolet rays, exhaust gas, etc. As an example, the protective layer is made of a resin material such as an acrylic urethane resin, a water-based acrylic resin, or a fluororesin, or polymer mortar, which has a tensile elongation (elongation) equal to or greater than that of the shielding layer 50.

[0055] The reinforcing structure 10 may not have the primer 20. Therefore, the structure may be configured so that the unevenness correcting material 30 is applied directly to the surface of the structure 90. The reinforcing structure 10 may also have a structure that does not have the primer 20 or the unevenness correcting material 30. Therefore, the shielding layer 50 may be formed directly on the surface of the structure 90. The reinforcing structure 10 may also have a structure that has the primer 20 but does not have the unevenness correcting material 30. Therefore, the shielding layer 50 may be formed directly on the surface of the primer 20.

[0056] (Construction method) Next, a description will be given of a construction method for constructing the above-mentioned reinforcement structure 10 on the structure 90. Note that, since the reinforcement structure 10 is formed by this construction method, this construction method can also be said to be a manufacturing method for manufacturing the reinforcement structure 10.

[0057] In this construction method, first, a surface preparation is carried out to remove protrusions on the surface of the structure 90 and deposits (for example, deteriorated layers) attached to the surface, and then the primer 20 is applied.

[0058] Next, the unevenness correcting material 30 is applied to the surface to which the primer 20 has been applied, to smooth out the irregularities on the surface.

[0059] Next, a fiber sheet 40 is adhered to the surface coated with the unevenness correction material 30 using a shielding resin. Specifically, a base coat of shielding resin is applied, and the fiber sheet 40 is attached to the base coat of shielding resin and degassed. Then, a top coat of shielding resin is applied and degassed. The shielding resin is hardened, for example, by exposure to ambient temperature or by heating. This forms a shielding layer 50 with the fiber sheet 40 disposed therein.

[0060] When a protective layer is formed on the surface of the shielding layer 50 , the resin that forms the protective layer is applied to the surface of the shielding layer 50 .

[0061] (Method for detecting cracks in structure 90) Next, a crack detection method for detecting a crack occurring in the structure 90 in the reinforced structure 10 will be described.

[0062] In this crack detection method, first, light (specifically, ultraviolet light) is irradiated onto the shielding layer 50. Here, in the reinforcement structure 10, when a push-out load test is performed on the fiber sheet 40 and the shielding layer 50 as described above, the shielding layer 50 breaks before the fiber sheet 40. That is, in the reinforcement structure 10, when a tensile force in the planar direction or a shear force in the normal direction to the surface of the structure 90 acts on the fiber sheet 40 and the shielding layer 50, the shielding layer 50 breaks before the fiber sheet 40.

[0063] Therefore, when a crack occurs in the structure 90 and the surface of the structure 90 expands in the planar direction, or when a crack occurs in the structure 90 and a shear shift occurs on the surface of the structure 90, the shielding layer 50 can be broken and the fiber sheet 40 can be exposed, as shown in Figure 2, while the fiber sheet 40 is not broken.

[0064] That is, in the reinforcement structure 10, when a crack occurs in the structure 90, the shielding layer 50 breaks and the fiber sheet 40 is exposed from the broken portion. As a result, when light is irradiated toward the shielding layer 50, the exposed fiber sheet 40 emits light. In each figure including Fig. 2, the light irradiated toward the shielding layer 50 is indicated by the symbol L1, and the light emitted by the fiber sheet 40 is indicated by the symbol L2.

[0065] Next, the luminescence of the fiber sheet 40 is detected to detect cracks that have occurred in the structure 90. The luminescence may be detected visually or by using a photographing camera.

[0066] The occurrence of a crack is a concept that includes both a case where a crack occurs from a state where no crack has occurred and a case where the opening of an already occurring crack propagates. Therefore, a crack that has occurred in the structure 90 is a concept that includes both a crack that has occurred in the structure 90 in a state where no crack has occurred and a crack that has occurred as a result of the opening of an already occurring crack propagating. Furthermore, the mode of the crack includes not only a case where an opening occurs in the surface direction but also a case where a step occurs in the shear direction.

[0067] In this embodiment, as described above, the light emitted from the fiber sheet 40 is detected to detect cracks occurring in the structure 90.

[0068] (Effects of this embodiment) The effects of this embodiment will be described below in comparison with a comparative structure 100 shown in FIG.

[0069] The comparative structure 100 shown in FIG. 3 comprises a light-emitting layer 170 applied to the surface of a structure 90 and having a light-emitting material dispersed therein, and a shielding layer 150 applied to the surface of the light-emitting layer 170 and having a shielding material dispersed therein, and the elongation of the shielding layer 150 is made smaller than that of the light-emitting layer 170 so that only the shielding layer 150 breaks when a crack occurs in the structure 90.

[0070] In the comparative structure 100 shown in Figure 3, when a crack occurs in the structure 90, the light-emitting layer 170 extends in the planar direction and only the shielding layer 150 breaks. When light is irradiated toward the shielding layer 150, the light passes through the broken portion of the shielding layer 150, causing the light-emitting layer 170 to emit light, and the crack that has occurred in the structure 90 can be detected.

[0071] However, in the comparative structure 100 shown in FIG. 3 , it is difficult to adjust the elongation of the shielding layer 150 and the light-emitting layer 170 so that only the shielding layer 150 breaks when a crack occurs in the structure 90. If both the shielding layer 150 and the light-emitting layer 170 break when a crack occurs in the structure 90, as shown in FIG. 4 , the light-emitting layer 170 will not emit light even when irradiated with light, making it impossible to detect cracks in the structure 90. Furthermore, the primer layer 20 and the uneven laminated timber 30 may reduce the sensitivity for detecting damage to the structure, and without these, it becomes more difficult to adjust the elongation of the light-shielding layer 150 and the light-emitting layer 170. Furthermore, while it has been considered to place reinforcing fibers such as carbon fiber or glass fiber in the light-emitting layer 170, this reduces the sensitivity for detecting cracks because it makes it difficult for the light-shielding layer 150 to strain enough to break.

[0072] In contrast, in the reinforcement structure 10 of this embodiment, the illuminant that emits light when irradiated with light is a fiber sheet 40, so compared to the comparative structure 100 shown in Figure 3, it is possible to make the structure such that the illuminant is less likely to break not only when the surface of the structure 90 expands in a direction along the surface, but also when it is damaged in such a way that a step is created, thereby reducing the possibility of failure to detect cracks in the structure 90.

[0073] Furthermore, in the reinforcement structure 10, the entire shielding layer 50, including the portion where the fiber sheet 40 is adhered to the structure 90 (hereinafter referred to as the adhesion portion), can be broken before the fiber sheet 40, so even if the construction surface is uneven, the fiber sheet 40 is easily exposed and emits a large amount of light when irradiated with light. This also helps prevent failure to detect cracks in the structure 90.

[0074] Furthermore, with the reinforcement structure 10, the shielding layer 50 also serves as an adhesive layer, eliminating the need for a material for adhering the fiber sheet 40 in addition to the material for forming the shielding layer 50, and allowing the use of materials optimal for construction, thereby reducing material costs, simplifying material management, and facilitating construction.

[0075] Furthermore, in the reinforcement structure 10, the entire shielding layer 50, including the adhesive portion, is made of the same material, so the breaking strength is the same throughout the entire shielding layer 50, and the variation in breaking timing throughout the entire shielding layer 50 is reduced.

[0076] Furthermore, in this structure, the shielding layer 50 also serves as an adhesive layer, which is highly effective in shielding the fiber sheet 40. Therefore, false detection due to the fiber sheet 40 being inadvertently exposed can be suppressed.

[0077] In addition, since this structure has the fiber sheet 40, it not only has the effect of preventing fragments from falling off when damage occurs to the structure 90, but also has the effect of reinforcing the structure 90, which the comparative structure 100 does not have.

[0078] Second Embodiment (Reinforcement structure 12) Next, a reinforcement structure 12 according to a second embodiment will be described. Fig. 5 is a cross-sectional view showing the reinforcement structure 12 according to this embodiment. Fig. 6 is a cross-sectional view showing the reinforcement structure 12 according to this embodiment in a state where the shielding layer 50 and an adhesive layer 70 (described below) have been broken. Note that parts having the same functions as those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0079] In the first embodiment described above, the fiber sheet 40 was adhered to the surface of the structure 90 by the shielding layer 50, but in the second embodiment, the adhesive layer that adheres the fiber sheet 40 and the shielding layer are formed as separate layers. That is, in the second embodiment, the adhesive function of adhering the fiber sheet 40 and the shielding function of shielding the fiber sheet 40 are functionally separated.

[0080] Specifically, as shown in FIG. 5, the reinforcement structure 12 of the second embodiment includes a primer 20, an unevenness correcting material 30, a fiber sheet 40, an adhesive layer 70, and a shielding layer 50.

[0081] The adhesive layer 70 has the function of adhering the fiber sheet 40 to the structure 90. Specifically, the adhesive layer 70 is formed by applying an adhesive resin to the surface of the unevenness correction material 30 and then curing it. As an example, a resin such as an epoxy resin is used for the adhesive layer 70. Note that the adhesive layer 70 is not limited to an epoxy resin, and may be a resin other than an epoxy resin, such as an acrylic resin, or other thermosetting resin. Although various materials can be used for the adhesive layer 70, a solvent-free room-temperature curing epoxy resin is preferably used.

[0082] The adhesive layer 70 does not contain any shielding material and is a transparent layer, allowing the fiber sheet 40 to transmit light that produces a luminous effect.

[0083] In the reinforcement structure 12 of the second embodiment, the shielding layer 50 is specifically formed by applying a shielding resin to the surface of the adhesive layer 70 and then curing it.

[0084] Here, in the reinforced structure 12, when a punching load test is performed on the fiber sheet 40, the adhesive layer 70, and the shielding layer 50, the adhesive layer 70 and the shielding layer 50 break before the fiber sheet 40. In the punching load test, a tensile force in a direction along the surface of the structure 90 (hereinafter referred to as the planar direction) and a shear force in a direction normal to the surface act on the fiber sheet 40, the adhesive layer 70, and the shielding layer 50. Therefore, in the reinforced structure 12, when a tensile force in the planar direction or a shear force in the direction normal to the surface of the structure 90 acts on the fiber sheet 40, the adhesive layer 70, and the shielding layer 50, the adhesive layer 70 and the shielding layer 50 break before the fiber sheet 40.

[0085] Therefore, when a crack occurs in the structure 90 and the surface of the structure 90 expands in the planar direction, or when a crack occurs in the structure 90 and a displacement occurs in the shear direction on the surface of the structure 90, the adhesive layer 70 and the shielding layer 50 will break while the fiber sheet 40 remains intact, as shown in Fig. 6. Therefore, the reinforcement structure 12 is configured such that when a crack occurs in the structure 90, the adhesive layer 70 and the shielding layer 50 break and the fiber sheet 40 is exposed from the broken portion.

[0086] For example, the "Punching Load Test" described in Appendix 17-2, Test Methods for Concrete Surface Coating Methods, of the Standard Specifications for Civil Engineering Works (edited by East Japan Railway Company) and the Japan Railway Facilities Association (September 2016) is used as the punching load test.

[0087] Furthermore, in the reinforcement structure 12, when the tensile elongation (elongation) in the plane direction of the fiber sheet 40 is compared with that of the adhesive layer 70 and the shielding layer 50, the tensile elongation (elongation) of the fiber sheet 40 is greater than that of the adhesive layer 70 and the shielding layer 50. Specifically, the elongation of the fiber sheet 40 is, for example, 20-something percent, and the elongation of the adhesive layer 70 and the shielding layer 50 is, for example, 3% or less, preferably 0.5% or more and 3% or less, and more preferably 0.5% or more and 2.5% or less (all elongations at 23°C). Note that these elongations are the breaking elongation (i.e., the value obtained by dividing the elongation between the gauge points of the tensile test piece after breaking by the gauge length and expressing it as a percentage).

[0088] Regarding the tensile elongation (elongation) in the plane direction between the adhesive layer 70 and the shielding layer 50, the tensile elongation (elongation) of the shielding layer 50 is set to be equal to or greater than that of the adhesive layer 70. If the adhesive layer 70 has a larger elongation, the adhesive layer 70 will remain even if the light-shielding layer 50 breaks, which is undesirable because it will physically block the light emission of the light-emitting fiber due to excitation light (ultraviolet light).

[0089] Similar to the reinforcing structure 10, the reinforcing structure 12 may also have a protective layer formed on the surface of the shielding layer 50 to protect the shielding layer 50. Examples of the protective layer include resin materials such as acrylic urethane resin, water-based acrylic resin, and fluororesin, which have a tensile elongation (elongation) equal to or greater than that of the shielding layer 50, or polymer mortar.

[0090] (Construction method) Next, a description will be given of a construction method for constructing the above-mentioned reinforcement structure 12 on the structure 90. Note that, since the reinforcement structure 12 is formed by this construction method, this construction method can also be said to be a manufacturing method for manufacturing the reinforcement structure 12.

[0091] In this construction method, first, a surface preparation is carried out to remove protrusions on the surface of the structure 90 and deposits (for example, deteriorated layers) attached to the surface, and then the primer 20 is applied.

[0092] Next, the unevenness correcting material 30 is applied to the surface to which the primer 20 has been applied, to smooth out the irregularities on the surface.

[0093] Next, the fiber sheet 40 is adhered to the surface coated with the unevenness correction material 30 using an adhesive resin. Specifically, an undercoat of adhesive resin is applied, the fiber sheet 40 is attached to the undercoat of adhesive resin, and the resin is degassed. Then, a top coat of adhesive resin is applied and the resin is degassed. The adhesive resin is hardened, for example, by exposure to ambient temperature or by heating. This forms an adhesive layer 70 with the fiber sheet 40 disposed therein.

[0094] Next, a shielding resin is applied to the surface of the adhesive layer 70. The shielding resin is cured, for example, at ambient temperature or by heating. In this way, the shielding layer 50 is formed.

[0095] When a protective layer is formed on the surface of the shielding layer 50 , the resin that forms the protective layer is applied to the surface of the shielding layer 50 .

[0096] (Method for detecting cracks in structure 90) Next, a crack detection method for detecting a crack occurring in the structure 90 in the reinforcement structure 12 will be described.

[0097] In this crack detection method, first, light (specifically, ultraviolet light) is irradiated onto the shielding layer 50. Here, in the reinforced structure 12, when a push-out load test is performed on the fiber sheet 40, adhesive layer 70, and shielding layer 50, the adhesive layer 70 and shielding layer 50 break before the fiber sheet 40. That is, in the reinforced structure 12, when a tensile force in the planar direction or a shear force in the normal direction to the surface of the structure 90 acts on the fiber sheet 40, adhesive layer 70, and shielding layer 50, the adhesive layer 70 and shielding layer 50 break before the fiber sheet 40.

[0098] Therefore, when a crack occurs in the structure 90 and the surface of the structure 90 expands in the planar direction, or when a crack occurs in the structure 90 and a shear shift occurs on the surface of the structure 90, as shown in Figure 6, the adhesive layer 70 and the shielding layer 50 can be broken, exposing the fiber sheet 40, while the fiber sheet 40 is not broken.

[0099] That is, in the reinforcement structure 12, when a crack occurs in the structure 90, the adhesive layer 70 and the shielding layer 50 break, exposing the fiber sheet 40 from the broken portion. As a result, when light is irradiated toward the shielding layer 50, the exposed fiber sheet 40 emits light.

[0100] Next, the luminescence of the fiber sheet 40 is detected to detect cracks that have occurred in the structure 90. The luminescence may be detected visually or by using a photographing camera.

[0101] In this embodiment, as described above, the light emitted from the fiber sheet 40 is detected to detect cracks occurring in the structure 90.

[0102] (Effects of this embodiment) In the reinforcing structure 12 of this embodiment, the illuminant that emits light when irradiated with light is a fiber sheet 40. Therefore, compared to the comparative structure 100 shown in Figure 3, it is possible to make the structure such that the illuminant is less likely to break not only when the surface of the structure 90 expands in a direction along the surface, but also when it is damaged in such a way that a step is created, thereby reducing the possibility of failure to detect cracks in the structure 90.

[0103] Furthermore, in the reinforcement structure 12, both the adhesive layer 70 and the shielding layer 50 can be broken before the fiber sheet 40, so even if the construction surface is uneven, the fiber sheet 40 is easily exposed, and the amount of light emitted when irradiated with light is increased. This also helps to prevent failure to detect cracks in the structure 90.

[0104] In addition, since this structure has the fiber sheet 40, it not only has the effect of preventing fragments from falling off when damage occurs to the structure 90, but also has the effect of reinforcing the structure 90, which the comparative structure 100 does not have.

[0105] (Evaluation test) In this test, the reinforcement structure of the first embodiment described above was evaluated as to whether it could provide a reinforcement effect and whether it was possible to detect cracks in the structure by light emission.

[0106] [Material composition] The following materials were used as the primer 20, the unevenness correction material 30, the fiber sheet 40, and the shielding resin and shielding material that make up the shielding layer 50. The primer 20, the unevenness correction material 30, and the shielding resin are manufactured by Nippon Steel Chemical & Material Co., Ltd. For the fiber sheet 40, luminescent fibers were arranged on one layer of plain weave nylon sheet.

[0107] <Example> Primer 20: Epoxy resin (product name: FP-NS) 0.2 kg / m 2 Unevenness correction material 30: Epoxy resin (product name: FE-Z) 1.0 kg / m 2 Fiber sheet 40: Plain woven nylon sheet 180g / m 21 layer + luminous fiber (polyester fiber treated with fluorescent whitening agent) Shielding resin: Epoxy resin (product name: FR-E5P) Shielding material: 15 parts by mass of titanium oxide, 0.4 parts by mass of carbon black

[0108] <Comparative Example> Primer 20: Epoxy resin (product name: FP-NS) 0.2 kg / m 2 Unevenness correction material 30: Epoxy resin (product name: FE-Z) 1.0 kg / m 2 Fiber sheet 40: Plain woven nylon sheet 180g / m 2 1 layer + luminous fiber (polyester fiber treated with fluorescent whitening agent) Shielding resin: Epoxy resin (product name: FR-E3P) Shielding material: 15 parts by mass of titanium oxide, 0.4 parts by mass of carbon black

[0109] As described above, the comparative example uses an epoxy resin (product name: FR-E3P) as the shielding resin, which has different physical properties from the epoxy resin (product name: FR-E5P) used in the example. Except for this, the comparative example has the same configuration as the example.

[0110] [Test method] The test method used was the "Punch-out Load Test" described in Appendix 17-2, "Test Methods for Concrete Surface Coating Methods," of the Standard Specifications for Civil Engineering Works (edited by East Japan Railway Company) and the Japan Railway Construction Association (September 2016). Specifically, the "Punch-out Load Test" is performed as shown in FIG. 7. Specifically, each layer of the reinforcement structure 10 (primer 20, unevenness correction material 30, fiber sheet 40, and shielding layer 50) is formed on a concrete structure (structure 90), and the formed surface is supported on a support 202 with the formed surface facing downward, as shown in FIG. 7. The concrete structure is then punched from above with an indenter 204. During this punch-out process, the fiber sheet 40, the shielding layer 50, and other components are pulled in the planar direction, and shear forces are also applied in the normal direction.

[0111] [Reinforcement effect] As a result of the test, in the example, a maximum load of 5326 N (displacement: 52 mm) was measured, as shown in the graph in Figure 8. Since the required performance for reinforcement is approximately 1500 N or more, it was confirmed that there was a reinforcing effect.

[0112] [Check the light] In the example, as shown in the photograph of FIG. 9, light emission was confirmed from the crack in the shielding layer 50 (the area surrounded by a solid line in FIG. 9) at a displacement of 40 mm. This indicates that the shielding layer 50 broke along with the crack in the structure 90, exposing the fiber sheet 40. Furthermore, it can be said that this indicates that the structure is such that the shielding layer 50 breaks before the fiber sheet 40 when tension in the planar direction and shear force in the normal direction are applied to the fiber sheet 40 and the shielding layer 50. It was also confirmed that the reinforcement structure of this embodiment makes it possible to detect cracks occurring in a structure by irradiating ultraviolet light toward the shielding layer 50.

[0113] In the configuration of the example, the breaking elongation was measured and, as a result, the breaking elongation was 3% or less, specifically, a value within the range of 1% to 2%, as shown in Figure 10. In the example, the breaking elongation was measured using five test specimens (A1 to A5), and the measurement results showed values ​​of 1.2% (see A1), 1.3% (see A2), 1.6% (see A3), 1.1% (see A4), and 1.0% (see A5).

[0114] On the other hand, in the comparative example, the shielding layer 50 did not break, and no light emission from the fiber sheet 40 was confirmed. When the breaking elongation was measured for the configuration of the comparative example, the breaking elongation showed a value of 4% or more, as shown in FIG. 11. In the comparative example, the breaking elongation was measured using five test specimens (B1 to B5), and all of the test specimens showed a value of 4% or more. Thus, it is presumed that the breaking elongation value was larger in the comparative example than in the example, and therefore the shielding layer 50 did not break.

[0115] The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements are possible without departing from the spirit of the present invention. For example, the above-described modified examples may be appropriately combined to form a configuration. [Explanation of symbols]

[0116] 10, 12 Reinforcement structure 20 Primers 30 Unevenness correction material 40 Fiber Sheet 50 shielding layer 70 Adhesive layer 90 Structures

Claims

1. a fiber sheet disposed on the surface of the structure and containing fibers that emit light when irradiated with light; an adhesive layer that adheres the fiber sheet to the surface; a shielding layer that blocks light irradiated onto the fiber sheet; Equipped with When a punching load test is performed on the fiber sheet, the adhesive layer, and the shielding layer, the adhesive layer and the shielding layer break before the fiber sheet. Reinforced structure.

2. a fiber sheet disposed on the surface of the structure and containing fibers that emit light when irradiated with light; an adhesive layer that adheres the fiber sheet to the surface; a shielding layer that blocks light irradiated onto the fiber sheet; Equipped with When a crack occurs in the structure, the adhesive layer and the shielding layer are broken, and the fiber sheet is exposed from the broken portion. Reinforced structure.

3. The shielding layer also serves as the adhesive layer. The reinforcement structure according to claim 1 or 2.

4. A crack detection method for detecting cracks occurring in a structure by irradiating light onto the reinforcement structure according to any one of claims 1 to 3 and detecting the light emitted from the fiber sheet.

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